Rocker support for bucket attachment



Aug. 19, 1969 G. w; MoRK 3,462,029

ROCKER SUPPORT FOR BUCKET ATTACHMENT l Filed Feb. 2, 1968 2 Sheets-Sheet 1 iii-lllI-ui'za.-

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INVENTOR G EORGE W. MORK ATTORNEv Y A g. 19, 1969 I G. w. MCRK l 3,462,029

' ROGKER SUPPORT FOR BUCKET ATTACHMENT Filed Feb. 2. 1968 l 2 Sheets-Sheet f5 INVENTOR 'GEORGE W. MORK MQW/w ATTORNEY United States Patent O U.S. Cl. 214-138 5 Claims ABSTRACT OF TI-IE DISCLOSURE A support for the clamshell bucket attachment of a stick clam excavator comprises a rst bracket attached to an excavator stick and including parallel depending plates provided with rocker openings having elongated, at bottom edges transverse to the plane of movement of the stick. A second bracket attached to a bucket assembly includes spaced arms between the plates which carry rocking lugs. The lugs are received in the openings and are rockable therein to allow limited transverse pivotal motion of the bucket assembly; and have elongated, flat bottom edges which are in alignment and engageable with the bottom edges of the openings to minimize oscillation of the attachment. The upper edges of the openings and lugs are shaped to define sets of facing, centrally located relatively closely spaced tapered thrust bosses which take initial thrust loads and minimize lost motion between the two brackets, but which can slide past one another in either direction to allow rocking.

Background of the invention This invention relates, but is not limited to, excavating machines of the type known as stick claims, in which a clamshell bucket attachment is connected directly to the end of a live stick or boom so that the stick can be used to force the bucket downwardly into the ground. It resides more specifically in a support for such a bucket attachment which provides the necessary rigidity to allow the stick to force the bucket down but still allows a desirable limited freedom of movement in a transverse plane to compensate for uneven ground conditions.

lIt is conventional to mount the bucket attachment of a stick clam on a transverse pin at the tip of the stick so that it is relatively free to pivot in the same plane as the stick, this freedom being necessary to keep the attachment vertical as the stick is raised or lowered. It is also desirable to provide for some freedom of movement in a transverse plane, however, to accommodate for uneven ground conditions; and it has been proposed, for example in U.S. Patent No. 2,755,946, issued July 24, 1956 to I. I. Bevan, to accomplish this simply by providing a second pin connection below and perpendicular to the rst. Having a second pin provides relatively unlimited transverse pivotability, however, and as a result is not particularly desirable. For one thing, free transverse pivotability reduces the rigidity of the support and could make it dicult to apply substantial digging force with the stick without causing a transverse buckling. Further, the free transverse pivotability could result in undesirable lateral oscillation of the bucket as the stick is being swung between digging and dumping areas.

Summary of the invention It is the general object of this invention to provide a support for a bucket attachment which provides the necessary rigidity for effective digging but which also provides for a limited transverse pivotability.

It is a specific object of the invention to provide a rocker type support including rocking lugs which have elongated, at bottom edges that are aligned and engageable with elongated at bottom edges of rocker openings. Transverse pivotal movement in either direction causes the lugs to rock about their oposite edges so that there is a moment arm which helps to urge the bucket attachment to return to a vertical position, and minimizes oscillation.

Another specific object is to provide a rocking lug and opening in which the top edge of the opening is engageable with the lug to limit a rocking motion.

Still another specific object of the invention is to provide a construction in which a lug is rockable in an opening, but where both the lug and the opening are shaped to provide centrally located, facing thrust bosses which minimize lost motion and take initial thrust loads while being capable of sliding past one another in either direction to allow for rocking.

The invention also contemplates the provision of a support having all of the foregoing and other advantages which is mechanically strong and adaptable to large machines while being relatively simple and inexpensive to manufacture, assemble and maintain.

Brief description of the drawings FIG. 1 is a schematic side view in elevation of a stick clam excavator incorporating a bucket attachment support according to this invention,

FIG. 2 is an enlarged fragmentary end view in elevation, partially broken away and with a tilted or rocked position of the bucket attachment shown in broken lines, showing the support of PIG. l, and

FIG. 3 is an enlarged fragmentary side view in elevation, with parts shown broken away and in cross section. further illustrating the support of FIG. 1.

Description of the preferred embodiment The machine shown in FIG. 1 of the drawings is a generally conventional stick clam type of excavator, and for that reason it is not shown and will not be described in detail. In general, the machine includes a main frame 1 which is revolvably mounted on a crawler base 2. A boom 3 is footed on the frame 1 and is actuated in a vertical plane by means of a pair of parallel hydraulic hoist cylinders 4, only one of which can be seen in FIG. l. A handle or stick 5 is pivotally mounted at the end of the boom 3 and is actuated in the same vertical plane by means of a hydraulic digging cylinder 6. A clamshell bucket attachment designated generally by .the reference numeral 7 is mounted at the end of the stick 5 by means of the support which constitutes this invention and which will be described in detail hereinafter.

The bucket attachment 7 shown in FIG. 1 is of the type shown and described in detail in the copending application of George W. Mork and Carl F. Novotny, Ser. No. 702,728, led Feb. 2, 1968 to which reference may be had for a more detailed description. It comprises, in essence, a hydraulic cylinder casing 8, a cross head housing 9 attached to the rod end of the casing `8, and bucket halves 10 pivotally mounted at the outer end of the housing 9. The rod (not shown) of the cylinder 8 operates in the housing 9 to move a cross head 11 which extends outwardly on opposite sides of the housing 9 and is connected to respective bucket halves 10 by thrust links 12, extension and retraction of the rod obviously causing opening and closing of the bucket halves 10. Although this particular type of bucket attachment is highly satisfactory, it would be possible to use other types of attachments known to the art with the support of this invention, and the invention is not necessarily limited to the particular attachment 7 that is shown.

The support for the bucket attachment 7 comprises a first or upper bracket designated generally by the reference numeral 13 which is pivotally attached to the end of the stick by means of a transverse pin 14. As will be seen, the entire bucket attachment 7 in effect depends from the bracket 13, and, therefore, the pin 14 forms a conventional mounting for the bucket attachment 7 which allows it to pivot relatively freely in the same vertical plane as the stick 5 and boom 3.

The bracket 13 includes quill portions 15 on laterally opposite sides of the tip of the stick 5, which portions actually receive the pin 14, suitable means (not shown) being provided to lock the pin 14 in place. It further includes, as integral or attached members, opposite, generally U-shaped, downwardly depending support plates 16 which are connected at their upper ends to the quill portions 15 and have central thickened portions 17 parallel to and aligned with one another. Angled cover plates 18 extend between the outside side edges of tht plates 16 to form a generally enclosed unit.

The thickened portion 17 of each plate 16 is provided with a rocker opening 19, the two openings 19 being the same and in line with one another, and lying in parallel planes transverse to the plane of movement of the boom 3 and stick 5. The rocker openings 19 are generally rectangular in form, and have elongated, fiat bottom edges 20, which are also transverse to the planes of the boom 3 and stick 5. The top edge of each opening 19 is shaped to define a generally centrally located, downwardly facing tapered thrust boss 21 which has a flat thrust bearing surface 22 at its apex.

The support further comprises a lower or second bracket designated generally by the reference numeral 23. The bracket 23 includes a central or base portion 24 and spaced, plate-like, parallel upwardly extending arms 25 which are connected thereto by bolts 26. The arms 25 are received between and outwardly ,face respective support plates 16.

Each arm 25 carries an integral or attached rocker lug 27 which faces outwardly and is received in a respective rocker opening 19 to support the second bracket 23 from the first bracket 13. The lugs 27 are also of generally rectangular configuration and have elongated, fiat bottom edges 28 which are in alignment and engageable with the opening bottom edges 20. The upper edge of each lug 27 is shaped to define a generally central, tapered, upwardly facing thrust boss 29 having a fiat thrust bearing surface 30 at its apex.

The lugs 27 extend outwardly through the openings 19; and square cover plates 31 are secured to the laterally outermost surfaces of the lugs 27 by means of bolts 32. The plates 31 help in preventing the entry of dirt, pebbles, etc. which could clog up the rocker openings 19 or otherwise interfere with operation.

As can be seen best in FIG. 3, the base of the cylinder casing 8 is attached to the bracket base portion 24 by a rotatable connection 33 which can be of any suitable type known to the art and is, therefore, shown only schematically. Any suitable form of conventional hydraulic motor 34 is mounted on the base 24 and is operable through suitable circuitry (not shown) to effect rotation of the casing 8. This results in what is termed a swivel action in which the entire bucket attachment 7 can be rotated about its longitudinal axis. This allows the orientation of the bucket to be changed and is useful, for example, should it be desired to dig a wider trench or dig a trench parallel to the line of advance of the machine.

In the normal position shown in the drawings, in which the bucket attachment 7 is off the ground and hanging vertically, the second bracket 23 is in a lowered position with respect to the first bracket 13. In this position, the lugs 27 are at the bottoms of the openings 19 with the fiat lug bottom surfaces 28 fiat against the fiat bottom edges of the openings 19. In this position, respective thrust bosses 21 and 29 face and are in alignment with one another, with the surfaces 22 and 30 facing slightly separated vertically, all as can best be seen in full lines in FIG. 2.

During an actual digging operation, the bucket attachment 7 is first opened and then lowered by means of the stick 5, and/or the boom 3, until it rests on the ground. Further downward movement of the tip of the stick 5 will then, in effect, cause the rocker lugs 27 to move upwardly in the openings 19. The first phase of this movement, substantially regardless of whether the ground is level or not, will result in the two thrust bosses 21, 29 on each side being moved together. As soon as the surfaces 22, 30 meet, there is a direct butting connection between the stick 5 and bucket attachment 7 so that the stick 5 can then be used to force the bucket attachment 7 downwardly. Assuming that the ground is uneven transversely, however, the bucket attachment 7 is capable of tilting transversely to a position where the rocker lugs 27 have rocked to the position shown in dotted lines in FIG. 2, or to a corresponding position in the opposite direction. Once the dotted line position shown in FIG. 2 has been reached, no further transverse tilting in that direction is possible, however, since the top edge of the lug 27 engages the top edge of the opening 19 as seen, this being accomplished by having the height of the opening 19 less than the length of the lug 27 or by any other configuration providing the desired engagement. During movement to tilted or rocked position, the bosses 21, 29 simply slide past one another in either direction as required. Subsequent lifting of the stick 5 will of course allow the elements to resume their normal positions.

The transverse pivotal movement allowed by the rocker connection between the brackets 13, 23 is very important in compensating for laterally uneven ground conditions which might occur, for example, in digging along the side of a hill or where one side or half of the bucket hits a rock or is in harder ground. The concept of providing for such movement is of course not new per se, but the rocker construction shown provides a number of major advantages over any other known arrangement. First, using openings and lugs with elongated fiat bottom edges or surfaces transverse to the plane of the stick 5 is important in that it provides a moment arm tending to keep the bucket attachment 7 vertical at all times. That is, whenever the bucket attachment tilts, the lugs 27 rock about their opposite edges. As a result, there is a moment arm defined by the distance between the center of the lug and the edge about which it is rocking which resul-ts in there being a substantially greater tendency for the attachment 7 to return to vertical than if a cylindrical pin connection were used. The same moment arm tends to prevent tilting when the attachment is vertical, and thus, with the fiat edge configuration, minimizes lateral oscillation during swinging movements of the machine.

Second, having lthe lug in an opening where the top edge of the opening is spaced from the lug to allow rocking but is ultimately engageable with the lug to establish a direct connection and limit rocking is quite important. The purpose of providing for transverse pivotal motion 1s to compensate for minor or unseen unevenness, and it is assumed that the operator will not attempt to dig where the uneven conditions are excessive. Accordingly, it is quite desirable to have the tilting definitely limited so that the stick 5 can be used to push downwardly once there has been compensation. With a cylindrical pin connection, pushing down with the stick 5 could, even where there are only minor uneven conditions, result in a transverse buckling rather than in forcing the attachment 7 into the ground.

Third, the bosses 21, 29 are important. To provide for rocking of the lugs 27, it is obvious that there must be a substantial vertical distance between the top edges of the lugs 27 and the openings 19 when the elements are in normal position with the edges 28, 20 in engagement. This would ordinarily result in considerable undesirable lost motion before the bracket 13 could corne down and establish a direct connection between the top edges of the lugs 27 and openings 19, enabling the stick 5 to exert a downward force. The bosses 21, 29` minimize the gap and minimize lost motion by providing a quick initial engagement, but they can easily slide or move past one another in either direction so that they do not interfere with the desired tilting and ultimate nal engagement.

Fourth, the construction shown is obviously relatively simple, while being of great mechanical strength so that it is readily adaptable to large machines.

Although a preferred form of the invention has been shown and described herein, it will be obvious that modifications in structure or use might be made without departure from the spirit of the invention. The invention is clearly not limited to use in the particular machine shown, and it is equally obvious that various changes in the configurations and orientations of the several elements would be possible. By Way of only one example, it would be possible to have lugs on the upper bracket and openings in the lower bracket, which would be clearly equivalent to the construction shown. The invention is not intended, therefore, to be limited by the showing herein, by the precise language of the following claims, or in any other way except as clearly required.

I claim:

1. In a support for the bucket attachment of a stick clam excavator or the like, the combination comprising: a rst bracket adapted to be attached to a live excavator stick and including a downwardly depending support plate defining a rocker opening having an elongated at bottom edge; and a second bracket adapted to be connected to a bucket attachment and including an upwardly extending arm facing the plate and provided with a rocker lug that is received in the opening and that has an elongated at bottom edge aligned and engageable with the bottom edge of the opening, the top edges of the lug and opening being vertically spaced when the bottom edges are in engagement to allow the lug to rock with respect to the opening.

2. The combination of claim 1 wherein the top edges of the lug and opening are shaped to define centrally located, facing thmst bosses which, when the bottom edges are in engagement, are in alignment and spaced apart a distance less than the spacing between the top edges, the bosses being adapted to be moved directly against one another to transmit a force from one bracket to the other and to slide past one another in either direction to allow the lug to rock.

3. The combination of claim 1 wherein the top edge of the opening is engageable with the lug to limit rocking of the lug in the opening.

4. The combination of claim 3 wherein the top edges of the lug and opening are shaped to define centrally located, facing thrust bosses which, when the bottom edges are in engagement, are in alignment and spaced apart a distance less than the spacing between the top edges, the bosses being adapted to engage one another to transmit a force from one bracket to the other and to slide past one another in either direction to allow the lug to rock.

5. The combination of claim 4 wherein the first bracket has a pair of spaced plates, each with a rocker opening, the two openings being in parallel planes; and the second bracket has two spaced arms facing respective plates, each having a lug received in a respective opening.

References Cited UNITED STATES PATENTS 2,725,996 12/1955 Britton 214-147 2,755,946 7/1956 Bevan 214-147 HUGO O. SCHULZ, Primary Examiner U.S. Cl. X.R. 

